Article transfer apparatus

ABSTRACT

A series of articles are successively advanced in a step-by-step manner along a linear path by a transfer unit which includes a plurality of gripping members supported by parallel-spaced arms. The arms are supported for lateral movement relative to an elongated carriage which is supported for longitudinal movement. The arms are reciprocated as a unit by corresponding racks which engage pinions mounted on a splined shaft extending longitudinally of the carriage. The shaft is movable axially within a gear driven by a reversible stepping motor controlled by a pre-set control unit which also synchronously controls a reversible stepping motor for reciprocating the carriage. The control unit includes decade counters which may be adjustably set for precisely selecting the corresponding limits of longitudinal movement of the carriage and lateral movement of the arms and gripping members.

Jacobs 1451 Sept. 11, 1973 ARTICLE TRANSFER APPARATUS Orville W. Jacobs,Ludlow Falls,

Ohio

[73] Assignee: The East Dayton Tool & Die

Company, Dayton, Ohio [22] Filed: Jan. 10, 1972 [21] Appl. No.5 216,392

[75] lnventor:

[5 2] US. Cl. 214/1 BB, 198/218 Primary Examiner-Gerald M. ForlenzaAssistant Examiner-George F. Abraham Att0rneyWilliam R. Jacox et a1.

[57] ABSTRACT A series of articles are successively advanced in astepby-step manner along a linear path by a transfer unit which includesa plurality of gripping members supported by parallel-spaced arms. Thearms are supported for lateral movement relative to an elongatedcarriage which is supported for longitudinal movement. The arms arereciprocated as a unit by corresponding racks which engage pinionsmounted on a splined shaft extending longitudinally of the carriage. Theshaft is movable axially within a gear driven by a reversible steppingmotor controlled by a pre-set control unit which also synchronouslycontrols a reversible stepping motor for reciprocating the carriage. Thecontrol unit includes decade counters which may be adjustably set forprecisely selecting the corresponding limits of longitudinal movement ofthe carriage and lateral movement of the arms and gripping members.

8 Claims, 6 Drawing Figures PATENTEDSEPI 1 1 3.757. 961

SHEET 2 or 2 .98' M5 3 F I G 2 Y Illll 6 it; Q: 96 50 /5 I u .u I HI '72TRANSLATOR 1 1 W] 55 ADJUSTABLE PULSE 0/? OSCILLATOR GATE m 25 m DECADECOUNTERS BACKGROUND OF THE INVENTION This invention relates generally tothe form of article transfer apparatus or device disclosed in applicantsU. S. Pat. No. 3,025,731 which issued on Mar. 20, 1962. Such a transferdevice is particularly suited for successively advancing workpiecesbetween the dies of a punch press, but may be used for advancing otherforms of articles along a linear path to locate each article. at aseries of stations where successive operations are performed on thearticle. 7

When the transfer device shown in the above patent is used inconjunction with a punch press, the transfer device is connected by arod to the ram of the punch press so that the transfer device ismechanically operated in response to the reciprocating motion of thepunch or ram. As a result of this mechanical connection, only a portionof the ram stroke canbe used for transferring or advancing eachworkpiece between the dies on the press. That is, each workpiece mustusually be transferred or advanced quickly during the upstroke of theram, thus limiting the distance which the article can be transferredandalso usually requiring rapid acceleration and deceleration of theworkpiece so that it is difficult to obtain advancement of eachworkpiece in precise predetermined increments. It is therefore desirableto provide a transfer apparatus without these operating limitations.

It is also desirable for such a transfer apparatus to provide forconveniently and precisely adjusting the limits of movement of themembers which grip the workpieces or articles, both in a directionlaterally to the desired path of the articles and in a direction paral-'lel to the path of the articles. That is, convenient and precise lateraladjustment of the gripping members provides for quickly receiving andaccommodating articles of various sizes, and convenient and preciseadjustment of the longitudinal movement of the gripping members providesfor quickly selecting the distance of step-bystep advancement of eacharticle along the path.

SUMMARY OF THE INVENTION incremental steps of substantial distance. Thetransfer device is also adaptable for use in successively transfer-.ring each article between a series of presses or machines or between aseries of other stations where successive operations are performed oneach article. Furthermore, the transfer apparatus of the inventionprovides for using the maximum time available for successively advancingeach article and does not require that the transfer or advancement becompleted before the ram of a punch press starts its downward orextended stroke.

In accordance with the disclosed embodiment of the invention, the abovefeatures and advantages are generally provided by a transfer apparatuswhich includes an elongated carriage supported by a base frame for Ilongitudinal movement. A pair of parallel-spaced arms are supported bythe carriage for lateral movement relative to the carriage, and the armssupport a series of article gripping fingers or members. A rack ismounted on each arm and engages a corresponding pinion mounted on asplined shaft extending longitudinally of the carriage. The splinedshaft is movable axially within a gear driven by a reversiblesynchronous stepping motor controlled from a remote control unit whichprovides for conveniently selecting the number of steps made by thestepping motor in each direction of rotation.

The control unit also provides for selecting the number of steps made byanother reversible synchronous stepping motor which reciprocates thecarriage through a series of gears driving a rack mounted on the bottomof the carriage. Thus the control unit provides for operating thestepping motors in synchronism and for' precisely selecting the limitsof the movements of the gripping members in both a longitudinaldirection and in a lateral direction relative to the desired path forthe articles.

Other features and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENT The transfer apparatus disclosed in FIGS. 1 and 2 isparticularly suited for successively transferring a series of articles Aalong a linear path on the upper surface of an elongated platform ortable 12. For purposes of generally on the line generallyon the linegenerally on the line simplified illustration, the articles A arerepresented as cylindrical objects. However, it is to be understood thatthe articles A may be of any configuration. The transfer apparatusincludes a set of transfer units 15 which are positioned in generallyparallel opposed relation on opposite sides of the table 12 and thelinear path for the articles A. Since the transfer units 15 are ofsymmetrical construction, only one of the transfer units will bedescribed in detail.

Thus, each of the transfer units 15 includes an elongated cast orfabricated metal base frame 16 having a generally U-shapedcross-sectional configuration and defining an elongated trough-likechamber 17 therein. The frame is formed by a set of opposing side walls18 rigidly connected by a base wall 19, and each of the side walls 18includes a flat upper surface 21.

An elongated carriage 25 is supported for longitudinal movement by thebase frame 16 and includes an aluminum tubular portion 26 having arectangular cross-sectional configuration. The tubular portion 26 isrigidly secured to a generally rectangular solid aluminum bar portion 28having a pair of ribs or rails 29 projecting outwardly from the oppositeedges of the bar portion 28. The carriage rails 29 are engaged by a setof roller units 30 mounted on the upper surfaces 21 of the frame sidewalls 18. Each of the units 30 includes a base block 32 which supports apair of rollers 34 (FIG. 3) positioned above' and below thecorresponding rail 29 of the carriage 25. A third roller- 26 is alsosupported by each of the blocks 32 and is positioned to engage the outersurface of the corresponding rail 29. The rollers 34 and 36 incorporateantifriction bearings (not shown) and cooperate to support the carriage25 for smooth longitudinal movement with the minimum of friction.

An elongated rack 38 (FIG. 4) extends longitudinally of the carriage 25and is partially recessed within a longitudinally extending slot formedin the bottom surface of the solid bar portion 28 of the carriage 25.The rack 38 is engaged by a gear 41 (FIG. mounted on a shaft 42supported by a U-shaped bracket 44 positioned within the chamber 17. Thegear 41 is driven by a pinion 46 mounted on a shaft 47 which supportsanother gear 48 driven by another pinion 49. The pinion 49 is mounted ona shaft 51 which is connected by a flexible coupling 52 (FIG. 4) to theoutput shaft 53 a synchronous stepping motor 55. The motor 55 has aflange 56 which is secured to a tubular support member 58 projectingfrom the bracket 44, as shown in FIG. 4. One

form of stepping motor 55 which hasprovided satisfactory results ismanufactured by the Superior Electric Company and sold under thetrademark Slo-Syn. The specific motor used produces an output torque of400 ounce-inches and requires 200 pulses or steps .to produce onerevolution of the output shaft.

The stepping motor 55 is connected by a power supply line 59 to a remoteelectronic control unit 60 which includes a series of components as willbe explained later. The control unit 60 is preset by positioning aseries of control knobs 62 which are calibrated to produce movement ofthe carriage for a predetermined distance in steps or increments of0.0l0-inch. A set of control buttons 64 is positioned under the controlknobs 62 and provide for selecting on-off, jogging and continuousrunning operations of the stepping motor The carriage 25 supports a pairof elongated arms 68 each having longitudinally extending V-shapedgrooves 69 formed within its edge surfaces. The grooves 69 within eacharm 68 receive a set of correspondingly shaped rollers 72 each of whichis supported by an antifriction bearing (not shown) mounted on a shaft73 projecting upwardly from a base pad 74. Each of the pads 74 has adovetail way 76 which adjustably receives a corresponding mating plate77 rigidly secured to the flat upper surface of the carriage 25. Thusthe rollers 72 provide for movement of the arms 68 laterally withrespect to the carriage 25. A bar 79 rigidly connects the inwardlyprojecting end portions of the-arms 68 and also supports a series ofgripping members 80 each having a V-shaped notch 82 for receiving one ofthe articles A.

An elongated rack 84 is secured to the upper surface of each of the arms68 and is engaged by a corresponding gear or pinion 86 mounted on asplined shaft 88 extending longitudinally of the carriage 25. The endportions of the shaft 88 are rotatably supported by corresponding setsof bearings 89 mounted on blocks 91 which are rigidly secured to theupper surface of the carriage 25. Thus rotation of the shaft 88 iseffective to produce lateral movement of the gripping members 80 as aunit relative to the carriage 25.

Referring to FIGS. 1-3, an anti-friction bearing 94 is mounted on theshaft 88 between the pinions 86 and includes a series of balls (notshown) which project into the grooves defined between the splines on theshaft 88 so that the shaft 88 rotates with the bearing 94 but is free tomove axially within the bearing 94. The bearing 94 is rotatablysupported by an arm 96 which is rigidly secured to a bracket 97 mountedon an extension member 98 of the base frame 16.

A gear 99 (FIG. 3) is secured to the bearing 94 and engages a transfergear 101 rotatably supported by the arm 96. The gear 101 is driven by apinion 102 mounted on the output shaft 103 of another synchronousstepping motor 105 constructed substantially the same as the steppingmotor and mounted on the arm 96. An electrical power supply line 107connects the stepping motor 105 to the control unit which incorporatesanother set of control knobs 62 and push buttons 64 for preciselyselecting the rotation of the output shaft 103 of the stepping motor inboth forward and reverse directions. As mentioned above, each of themotors 55 and 105 requires 200 pulses or steps for each revolution ofits output shaft and is adapted to receive 3,000 steps per second sothat it will operate at 900 revolutions per minute. The correspondingmotors 55 and 105 of the opposing transfer units 15 are connected to thecontrol unit 60 for synchronous operation.

Referring to FIG. 6 the control unit 60 incorporates a control circuitfor each set of the stepping motors 55 or 105. The basic elements of thecircuit include an adjustable frequency oscillator 115, controlgates-116, decade counters 118 and a pulse-to-step translator logiccircuit 120. The decade counters 118 are set by the control knobs 62. Astart command signal is introduced at 122, for example, from a switchactuated by the movement of the ram of a punch press. This start signalcauses the gate circuits to pass pulses from the oscillator through apulse gate 123 to the decade counters 118 and to the translator logiccircuit 120. The translator logic circuit 120 converts the pulses intothe switching sequence required to rotate the output shaft of one set ofmotors 55 or 105. When the preselected count is completed, the controlgate 116 turns off the pulse gate 123 and actuates a relay 124 whichsupplies the start command pulse to the control circuit for the otherset of motors 55 or 105.

After the size of the articles A and the desired distance of advancementare determined, the control knobs 62 on the control unit 60 are setaccording to the desired limits of lateral movement of the grippingmembers 80 and of longitudinal movement of the carriages 25. When thestart signal is received, the motors 105 are actuated for thepreselected count to extend the gripping members 80 inwardly to engagethe corresponding articles A on the support table 12. The motors 55 arethen automatically energized to advance the carriages 25 by the desireddistance which corresponds to the spacing between the adjacent grippingmembers 80. The stepping motors 105 are then operated in a reversedirection to retract the gripping members 80 from the articles A, afterwhich the stepping motors 55 are actuated in a reverse direction toretract the carriages 25 to their starting or home positions. When thenext start signal is received, this sequence of operation is repeated sothat the gripping members 80 move in a rectangular path in timedrelation with the operation of the device which produces the startsignal.

From the drawings and the above description, it is apparent that anarticle transferapparatus constructed in accordance with the presentinvention, provides several desirable features and advantages. Forexample, one important feature is provided by the control of themovement of the gripping members 80 by the stepping motors 55 and 105and the control unit 60. This control system provides for using themaximum time available for advancing the articles and also provides forsmooth acceleration and deceleration at the beginning and at the end ofeach stroke of movement of the gripping members 80. Thus when thetransfer apparatus is being usedin conjuntion with a punch press, itisno longer necessary to complete the transfer or advancement of thearticles before the ram of the punch press begins its downward stroke.

The control system also provides for conveniently and preciselyadjusting the limits of movement of the gripping members 80 foraccommodating articles of various configurations and sizes and forprecisely selecting the distance of advancement of each article. Thatis, the limits of inward movement of thegripping members 80 and thetravel of the carriages 25 may be conveniently adjusted in increments of10, 1, 0.100 or 0.0l0 inches merely by adjusting one or more of thecontrol knobs 62. The spacing between the gripping members 80 on thebars 79 may also be quickly changed simply by shifting the grippingmembers on each bar. It is also apparent that the transfer apparatusprovides for moving the carriages 25 through long strokes by increasingthe count of the decade counter 118 which supplies the pulses to thestepping motors 55.

While the form of transfer apparatus herein described constitutes apreferred embodiment of the in vention, it is to be understood that theinvention is not limited to this precise form of apparatus, and thatchanges may be made therein without departing from the scope and spiritof the invention. For example, it is apparent that one of the transferunits may be replaced by a simple rail which extends along the platformor table 12 parallel to the movement of the carriage 25 of the othertransfer unit 15. The articles A would then be merely slid along therail in a step-bystep manner by the gripping members 80 of the singletransfer unit 15.

It is also within the scope of the invention to replace the steppingmotors 55 with hydraulic rotary motors which are supplied with hydraulicfluid from a pump and to use electrical stepping motors for operatingcontrol valves within the hydraulic fluid supply lines extending fromthe hydraulic pump 'to the hydraulic motors. This form of drive andcontrol system provides a substantially higher horsepower for drivingthe gears 41 and is desirable for reciprocating carriages 25 havingsubstantial mass. It is also apparent that a plurality of transfer units15 may be arranged in tandem relation between a series of machines andcontrolled from a single control unit 60 when it is desired tosuccessively advance a series of articles from one machine to the next.

The invention having thus been described the following is claimed:

1. Apparatus for transferring at least one article in a step-by-stepmanner along a predetermined path, comprising an elongated carriage,frame means supporting said carriage for longitudinal movement, grippermeans adapted to engage the article, a set of parallel spaced elongatedarms supporting said gripper means, means mounted on said carriage andsupporting said arms for longitudinal movement to effect lateralmovement of said gripper means relative to said carriage, alongitudinally extending splined shaft supported by said carriage, gearmeans for moving said arms longitudinally in response to rotation ofsaid shaft, a rotary drive member mounted on said shaft, said shaftbeing movable axially within said drive member, a first electricalstepping motor mounted on said frame means and having an output shaft,means for rotating said drive member in response to rotation of saidoutput shaft of said first stepping motor to effect gripping andreleasing of the article, an elongated longitudinally extending racksecured to said carriage, a second electrical stepping motor mounted onsaid frame means and having an output shaft, means for driving said rackin response to rotation of said output shaft of said second steppingmotor for reciprocating said carriage to effect intermittent successiveadvancement of the article after it has been gripped, means forproducing electrical pulses for each of said stepping motors and foractuating said stepping motors in synchronism, and control means forindependently selecting the number of pulses supplied to each of saidstepping motors for conveniently and precisely adjusting the limits ofmovement of said carriage and said gripper means. I

2. Apparatus as defined in claim 1 wherein said drive member includesexternalgear teeth, and said means for rotating said drive member inresponse to rotation of said output shaft of said first stepping motor,comprised a set of gears connecting said output shaft of said steppingmotor to said drive member.

3. Apparatus as defined in claim 1 wherein said means for drivingsaidrack in response to rotation of said output shaft of said secondstepping motor, comprise a set of gears connecting said output shaft ofsaid second stepping motor to said rack.

4. Apparatus as defined in claim 1 wherein said pulse producing meansinclude an adjustable frequency oscillator, said control means'include aset of pulse counters, a pulse-to-step translator logic circuit, andmeans responsive to an electrical start signal for controlling thetransfer of pulses from said oscillator to said counters and said logiccircuit.

5. Apparatus as defined in claim 1 wherein said gear means includes apinion on said splined shaft for each said arm, an, elongated rackmounted on each said arm and engaging the corresponding said pinion, andsaid member is mounted on said shaft between said pinions.

6. Apparatus as defined in-claim 1 wherein said carriage includesoutwardly projecting and longitudinally extending parallel side rails,and said supporting means for said carriage include a series of rollersengaging each of said rails.

7. An article transfer device including a pair of said apparatus asdefined in claim 1 and arranged in opposed relation, and said controlmeans is connected to actuate the corresponding said stepping motors insynchronism.

8. Apparatus for transferring at least one article in step-by-stepmanner along a predetermined path, comprising an elongated carriage,frame means supporting said carriage for longitudinal movement, grippermeans adapted to engage the article, a set of parallel spaed elongatedarms supporting said gripper means, means mounted on said carriage andsupporting said arms for longitudinal movement to effect lateralmovement of said gripper means relative to said carriage, alongitudinally extending splined shaft supported by said carriage, gearmeans for moving said arms longitudinally in response to rotation ofsaid shaft, a rotary drive gear mounted on said shaft between said arms,said shaft being movable axially within said drive member, bracket meansmounted on said frame means and supporting said drive gear for rotation,a first electrical reversible stepping motor mounted on said bracketmeans and having an output shaft, gear means connecting said drive gearto said output shaft of said first stepping motor to effect gripping andreleasing of the article, an elongated longitudinally extending racksecured to said carriage, a second electrical reversible stepping motormounted on said frame means and having a shaft, gear means connectingsaid rack to said output shaft of said second stepping motor forreciprocating said carriage to effect intermittent successiveadvancement of the article after it has been gripped, means forproducing electrical pulses for each of said stepping motors and foractuating said stepping motors in synchronism, means for counting thepulses, and control means for independently selecting the number ofcounted pulsessupplied to each of said stepping motors for convenientlyand precisely adjusting the limits of movement of said carriage and saidgripper means.

1. Apparatus for transferring at least one article in a step-bystepmanner along a predetermined path, comprising an elongated carriage,frame means supporting said carriage for longitudinal movement, grippermeans adapted to engage the article, a set of parallel spaced elongatedarms supporting said gripper means, means mounted on said carriage andsupporting said arms for longitudinal movement to effect lateralmovement of said gripper means relative to said carriage, alongitudinally extending splined shaft supported by said carriage, gearmeans for moving said arms longitudinally in response to rotation ofsaid shaft, a rotary drive member mounted on said shaft, said shaftbeing movable axially within said drive member, a first electricalstepping motor mounted on said frame means and having an output shaft,means for rotating said drive member in response to rotation of saidoutput shaft of said first stepping motor to effect gripping andreleasing of the article, an elongated longitudinally extending racksecured to said carriage, a second electrical stepping motor mounted onsaid frame means and having an output shaft, means for driving said rackin response to rotation of said output shaft of said second steppingmotor for reciprocating said carriage to effect intermittent successiveadvAncement of the article after it has been gripped, means forproducing electrical pulses for each of said stepping motors and foractuating said stepping motors in synchronism, and control means forindependently selecting the number of pulses supplied to each of saidstepping motors for conveniently and precisely adjusting the limits ofmovement of said carriage and said gripper means.
 2. Apparatus asdefined in claim 1 wherein said drive member includes external gearteeth, and said means for rotating said drive member in response torotation of said output shaft of said first stepping motor, comprised aset of gears connecting said output shaft of said stepping motor to saiddrive member.
 3. Apparatus as defined in claim 1 wherein said means fordriving said rack in response to rotation of said output shaft of saidsecond stepping motor, comprise a set of gears connecting said outputshaft of said second stepping motor to said rack.
 4. Apparatus asdefined in claim 1 wherein said pulse producing means include anadjustable frequency oscillator, said control means include a set ofpulse counters, a pulse-to-step translator logic circuit, and meansresponsive to an electrical start signal for controlling the transfer ofpulses from said oscillator to said counters and said logic circuit. 5.Apparatus as defined in claim 1 wherein said gear means includes apinion on said splined shaft for each said arm, an elongated rackmounted on each said arm and engaging the corresponding said pinion, andsaid member is mounted on said shaft between said pinions.
 6. Apparatusas defined in claim 1 wherein said carriage includes outwardlyprojecting and longitudinally extending parallel side rails, and saidsupporting means for said carriage include a series of rollers engagingeach of said rails.
 7. An article transfer device including a pair ofsaid apparatus as defined in claim 1 and arranged in opposed relation,and said control means is connected to actuate the corresponding saidstepping motors in synchronism.
 8. Apparatus for transferring at leastone article in step-by-step manner along a predetermined path,comprising an elongated carriage, frame means supporting said carriagefor longitudinal movement, gripper means adapted to engage the article,a set of parallel spaed elongated arms supporting said gripper means,means mounted on said carriage and supporting said arms for longitudinalmovement to effect lateral movement of said gripper means relative tosaid carriage, a longitudinally extending splined shaft supported bysaid carriage, gear means for moving said arms longitudinally inresponse to rotation of said shaft, a rotary drive gear mounted on saidshaft between said arms, said shaft being movable axially within saiddrive member, bracket means mounted on said frame means and supportingsaid drive gear for rotation, a first electrical reversible steppingmotor mounted on said bracket means and having an output shaft, gearmeans connecting said drive gear to said output shaft of said firststepping motor to effect gripping and releasing of the article, anelongated longitudinally extending rack secured to said carriage, asecond electrical reversible stepping motor mounted on said frame meansand having a shaft, gear means connecting said rack to said output shaftof said second stepping motor for reciprocating said carriage to effectintermittent successive advancement of the article after it has beengripped, means for producing electrical pulses for each of said steppingmotors and for actuating said stepping motors in synchronism, means forcounting the pulses, and control means for independently selecting thenumber of counted pulses supplied to each of said stepping motors forconveniently and precisely adjusting the limits of movement of saidcarriage and said gripper means.